From 67efe1f00fdcbba06ff63a6b129effabf1f8eaca Mon Sep 17 00:00:00 2001
From: Nitzan Uziely <nitzan@testim.io>
Date: Thu, 4 Feb 2021 15:31:47 +0200
Subject: [PATCH] events: change EventTarget handler exception behavior

Change the behavior of EventTarget, instead of emitting
'error' on handler exception, emit 'uncaughtException'.

Fixes: #36770
---
 doc/api/events.md                 |  3 +++
 lib/internal/event_target.js      | 12 ++++++------
 test/parallel/test-eventtarget.js | 12 +++++++-----
 3 files changed, 16 insertions(+), 11 deletions(-)

diff --git a/doc/api/events.md b/doc/api/events.md
index cd2d7fc6137945..0307bab2a990e2 100644
--- a/doc/api/events.md
+++ b/doc/api/events.md
@@ -1137,6 +1137,9 @@ setMaxListeners(5, target, emitter);
 <!-- YAML
 added: v14.5.0
 changes:
+  - version: REPLACEME
+    pr-url: https://github.com/nodejs/node/pull/37237
+    description: changed EventTarget error handling.
   - version: v15.4.0
     pr-url: https://github.com/nodejs/node/pull/35949
     description: No longer experimental.
diff --git a/lib/internal/event_target.js b/lib/internal/event_target.js
index 9dfbb8f9c4a5ce..2ec36095165fc1 100644
--- a/lib/internal/event_target.js
+++ b/lib/internal/event_target.js
@@ -459,9 +459,9 @@ class EventTarget {
           result = FunctionPrototypeCall(callback, this, arg);
         }
         if (result !== undefined && result !== null)
-          addCatch(this, result, createEvent());
+          addCatch(result);
       } catch (err) {
-        emitUnhandledRejectionOrErr(this, err, createEvent());
+        emitUncaughtException(err);
       }
 
       handler = next;
@@ -624,19 +624,19 @@ function isEventTarget(obj) {
   return obj?.constructor?.[kIsEventTarget];
 }
 
-function addCatch(that, promise, event) {
+function addCatch(promise) {
   const then = promise.then;
   if (typeof then === 'function') {
     FunctionPrototypeCall(then, promise, undefined, function(err) {
       // The callback is called with nextTick to avoid a follow-up
       // rejection from this promise.
-      process.nextTick(emitUnhandledRejectionOrErr, that, err, event);
+      emitUncaughtException(err);
     });
   }
 }
 
-function emitUnhandledRejectionOrErr(that, err, event) {
-  process.emit('error', err, event);
+function emitUncaughtException(err) {
+  process.nextTick(() => { throw err; });
 }
 
 function makeEventHandler(handler) {
diff --git a/test/parallel/test-eventtarget.js b/test/parallel/test-eventtarget.js
index 63c166fc1be421..771133e1150f36 100644
--- a/test/parallel/test-eventtarget.js
+++ b/test/parallel/test-eventtarget.js
@@ -178,14 +178,16 @@ let asyncTest = Promise.resolve();
 }
 
 {
-  const uncaughtException = common.mustCall((err, event) => {
+  const uncaughtException = common.mustCall((err, origin) => {
     strictEqual(err.message, 'boom');
-    strictEqual(event.type, 'foo');
+    strictEqual(origin, 'uncaughtException');
   }, 4);
 
-  // Whether or not the handler function is async or not, errors
-  // are routed to uncaughtException
-  process.on('error', uncaughtException);
+  // Make sure that we no longer call 'error' on error.
+  process.on('error', common.mustNotCall());
+  // Don't call rejection even for async handlers.
+  process.on('unhandledRejection', common.mustNotCall());
+  process.on('uncaughtException', uncaughtException);
 
   const eventTarget = new EventTarget();